Fluid actuated clamp



Jan. 9, 1968 I P. c. KOHLITZ 3,362,301

FLUID ACTUATED CLAMP Filed April 20, 1966 2 Sheets-$heet 1 I FIG.1.

INVENTO/P PAUl C AOl-IL/TZ A TTORNEVS Jan. 9, 1968 I P. c. KOHLITZ3,362,301

FLUID ACTUATEb CLAMP Filed April 20, 1966 2 Sheets-Sheet 2 FICS.3

' uvmewroe P402 c A a/{4 17-2 WLM A 7' TORNEKS' United States Patent3,362,301 FLUID ACTUATED CLAMP Paul C. Kohlitz, 5791 Beaconsfield Ave.,Detroit, Mich. 48234 Filed Apr. 20, 1966, Ser. No. 543,886 10 Claims.(Cl. 922) This invention relates to a fluid actuated clamp and, morespecifically, to a clamp of the type adapted for fixedly clamping aworkpiece on a fixture such as when a machining or similar operation isbeing performed on the workpiece.

Fluid operated clamps of the type described frequently consist of apiston-cylinder arrangement wherein the axially shiftable clamp isconnected to the piston and is caused to rotate through a predeterminedangle while it is being shifted axially between clamped and releasedpositions. The clamp is usually rotated through approximately 90 toenable the workpiece to clear the clamp when removed from the fixture.

One of the problems associated with such fluid actuated clamps relatesto the excessively long stroke required to rotate the clamp and to shiftit axially between the clamped and released positions. It is notuncommon in such arrangements to employ a spiral cam arrangement forrotating the clamp and shifting it axially in response to reciprocationof the piston in the cylinder.

It is an object of this invention to provide a fluid actuated clamp ofthe type described wherein the stroke required to rotate the clamp andto shift it axially is reduced to a minimum.

More specifically, it is an object of the present invention to provide aclamp of the type described which employs a main piston for shifting theclamp axially and a pair of auxiliary pistons connected to the mainpiston and adapted to rotate the main piston for rotating the clamp.

Other objects and features of the present invention will become apparentfrom the following description and drawings, in which:

FIGURE 1 is a sectional view through the fluid actuated clamp of thepresent invention showing the clamp in the clamped position.

FIGURE 2 is a sectional view along the line 2-2 in FIG. 1 and showingthe clamp in the released position.

FIGURE 3 is a cross sectional view taken along the line 3-3 in FIG. 2.

FIGURE 4 is a sectional view taken along the line 4-4 in FIG. 1.

FIG. 5 is a sectional view taken along the line 55 in FIG. 2.

Referring to the drawings, the clamp of the present invention includes ahousing which is preferably formed as a casting having a plurality oflugs 12 thereon adapted for mounting the housing on a support. Acylinder 14 is formed within housing 10 having one end thereof extendingto the end of the housing and closed by an end cap 16. The other end ofcylinder 14 is defined by an end wall 18. An axial bore 20 extends fromthe other end of housing 10 and into cylinder 14 at the center of endwall 18. The outer end of bore 20 is closed by a plug 21. A piston 22 isslidably arranged within cylinder 14 and is sealed therein by an O-ring24. A piston rod 26 is connected to piston 22 as by a pin 28. Rod 26extends -axially through end cap 16 and has a clamp arm 30 secured tothe outer end thereof as by a pin 32. Rod 26 extends through piston andits inner end 33 is splined as at 34. Splined portion 34 extends axiallythrough bore 20 and has a close sliding fit therein. The slidingconnection between end cap 16 and rod 26 is sealed by an O-ring 36; andthe peripheral connection between end cap 16 and cylinder 14 is sealedby an O-ring 38.

A second cylinder bore 40 is formed in housing 10. Cylinder 40 extendstransversely of cylinder 14 and is intersected by bore 20. Withincylinder 40 there is arranged a pair of opposed auxiliary pistons 42.Each piston 42 is sealed within cylinder 40 by an O-ring 44 and each endof cylinder 40 is closed by a plug 46 which is retained in place by asnap ring 48.

Referring now to FIG. 3, each piston 42 is fashioned with an axialextension 50 at one side thereof; the extensions 50 being formed withgear rack portions 52 engaging diametrically opposite sides of thesplined portion 34 of the inner end portion 33 of rod 26. With thisarrangement it will be observed that when pistons 42 are displacedtowards each other, rod 26 is rotated in a counterclockwise direction asviewed in FIG. 3, and when pistons 42 are displaced axially away fromone another, rod 26 is rotated in a clockwise direction.

Housing 10 is provided with a first port 54 which is threaded as at 56to receive an inlet fitting. Port 54 con nects with cylinder 14 througha restricted orifice 58. Housing 10 is fashioned with a pair ofpassageways 60 which at one end communicate with cylinder 14 throughdiametrically opposite ports 62 which are axially aligned with orifice58 and displaced 90 therefrom. The other ends of passageways 60communicate with the outer ends of cylinder 40 as at 64 and registerwith diametr-al slots 66 at the outer ends of pistons 42. The outer endof each piston 42 is fashioned with a central recess 68 with which theslots 66 communicate. Housing 10 is formed with a second port 70 whichis closed by a threaded plug 72. Plug 72 is fashioned with a threadedsocket 74 at its outer end for connecting with a fluid fitting. Plug 72is centrally apertured as at 76 so that socket 74 communicates withcylinder 14 adjacent the end wall 18 thereof. on the inner end of plug72 there is journalled a roller 78. Piston 22 is fashioned with a grooveat the end thereof facing end wall 18 with which roller 78 is adapted toregister end engage. Groove 80 is shown in broken lines in FIG. 2. Theaxial extent of groove 80 is not substantially greater than the diameterof roller 78.

As is clearly shown in FIGS. 1 and 2, piston 22 is formed with anannular shoulder 82 at one end thereof which registers with orifice 58and ports 62 when the pis ton is in abutting relation with end cap 16.When piston 22 is displaced axially toward end wall 18, roller 78engages the inner end of groove 80 so that there is a slight clearancespace 84 between the end of piston 22 and end wall 18 (FIG. 1). Thus,with the piston in the position illustrated in FIG. 1, if fluid underpressure is directed through plug 72, this fluid is permitted to flowthrough the groove 80, clearance space 84 and through the splines 34 ofthe end portion 33 of rod 26 into the portion of cylinder 40 between thetwo opposed auxiliary pistons 42.

End cap 16 is retained in fixed position Within the open end of cylinder14 by a bendable metal ring 86 which is adapted to seat in registeringcircumferential grooves 88 and 90 in housing 10 and end cap 16,respectively. As is illustrated in FIG. 5, housing 10 is slotted as at92 to expose a circumferential portion of groove 88. Ring 86 is providedwith a radial inwardly extending lug 94 at one end thereof adapted to beengaged in a socket 96 in end cap 16. The other end of the ring 86 istapered as at 98. With this arrangement it will be noted that ring 86can be threaded into and out of engagement with the registering grooves88, 90 by hooking lug 94 in socket 96 and rotating end cap 16. For thispurpose end cap 16 is fashioned with a pair of diametrically oppositesockets 100 in the exposed face thereof for engagement with a spannerwrench. To remove ring 86 it is only necessary to engage a prying toolunder the tapered end 92 of the ring and rotate end cap 16 in aclockwise direction, asviewed in FIG. 5, to thereby feed ring 86 out ofthe slotted portion 92.

In operation a source of fluid under pressure is connected with sockets"74 and 56. The pressure fluid may be compressed air; and the admissionof fluid to sockets 74 and 56 may be controlled by any suitable means,such as a solenoid valve, manual valve, etc. With the parts in thepositions illustrated in FIG. 1, it may be assumed that the clamping arm30 is engaging a flange or other portion of a workpiece and holding theworkpiece in clamped position on a fixture. If it is desired to releasethe workpiece, it is necessary to shift rod 26 to the right, as viewedin FIG. 1, and rotate clamping arm 30 90 to the position shown in FIG.2. To accomplish this, air under pressure is. admitted throughsocket 74to passageway '76. As previously explained, the air admitted throughpassageway 76 communicates with portion of cylinder 40 between the innerends of auxiliary pistons 42.

With the clamp in the engaged position the two auxiliary pistons 42 arein their inwardly retracted position. However, pressure fluid isincapable of displacing pistons 42 outwardly away from one anotherbecause piston 22 is locked against rotation by the interengagement ofroller 78 with groove 80. Thus, the pressure fluid acts against the endface 102 of piston 22 and displaces the piston axially to the right asviewed in FIGS. 1 and 2. When piston 22. is displaced from the positionshown in FIG. 1 to the position shown in FIG. 2, clamping arm 30 hasbeen released from clamping engagement with the workpiece and the endface 102 of piston 22 has cleared roller 78. At this time piston 22 isnot locked against rotation and thus the pressure fluid acting againstthe inner ends of auxiliarypistons 42 displaces the latter pistonsoutwardly away from each other. As pistons 42 are shifted axially awayfrom one another, the interengagement of the rack portions 50 with thespline portion 34 of rod 26 causes the rod and clamp arm 30 to rotate asindicated in FIG. 2. In the arrangement illustrated the rack and geararrangement produces rotation of clamping arm 30 through about 90. Inthis position of clamping arm 30 it has cleared the workpiece to permitready removal of the workpiece from the fixture.

When the clamp is in the released position shown in FIG. 2 and it isdesired clamp a workpiece to a work supportnig fixture, after theworkpiece is properly located on the fixture, fluid under pressure isdirected through port 56. Thepressure fluid exerts pressure against theshoulder 82 of piston 22 and by reason of passageways 60 also exertspressure against the outer ends of auxiliary pistons 42. As soon aspiston 22 shifts axially to the left slightly its end face 102 isengaged by roller 78 to arrest its axial displacement. However, piston22 is at this time free to rotate and the pressure fluid acting againstthe outer ends of pistons 42 displaces these pistons inwardly towardeach other and rotates piston 22. When groove 80 on piston 22 shiftscircumferentially to a position in alignment with roller '78 thepressure fluid acting against the opposite end face of piston 22displaces piston 22 to the left to the position shown in FIG. 1.Clamping arm 30 will thus havebeen rotated 90 and shifted axially withpiston rod 26 to a position clamping the workpieces on the fixture.

In addition to the advantage of requiring only a short 3 stroke torelease the clamping arm and rotate it, the

present clamp structure has several other important features. Forexample, with the arrangement described herein the clamping arm can berotated and shifted axially with relatively loW fluid pressure. Thisenables the present clamp structure to be used in clamping arrangementsfor the application of very heavy clamping pressure and also inconnection with relatively delicate workpieces where a very lightclamping pressure is desired.

Another important feature of the present invention resides in thearrangement whereby the direction of rotation of the clamping arm can bereversed by simply rotating the rack pistons 42 180 in cylinder 40. Suchrepositioning of rack pistons 42 would cause the splined portion 34' ofrod 26 to rotate in a direction opposite to that illustrated when thetwo rack pistons are shifted axially toward each other.

It will also be observed that in the arrangement illustrated the splinedportion 34 of rod 26 serves several desirable purposes. It provides adriving connection between the rack pistons and the main piston 22; itprovides a fluid passageway from the main cylinder bore 14 to the.

auxiliary cylinder bore and also provides axial support for piston 22 sothat in effect the main piston is axially supported at both its oppositeends.

I claim:

1. A fluid actuated clamp comprising means forming a first cylinder, apiston movable axially in said cylinder, a piston rod connected to thepiston, a clamp member operatively associated with the piston rod,locking means on the cylinder and piston adapted, when incircumferential registration, to interengage when the piston isdisplaced to one end of the cylinder for preventing rotation of thepiston and the clamp member, said piston being displaceable toward theother end of the cylinder to release said locking means and therebypermit rotation of the piston and the clamp member, means forming asecond cylinder, 2. second piston movable axially in the secondcylinder, means operatively interconnecting said first and secondpistons for causing rotation of the first piston andclamp in response toaxial displacement of the second piston in its cylinder and means forconducting pressure fluid to one side of both pistons and then to theopposite side of each piston, whereby when the first piston and cylinderare interengaged by said locking means and pressure fluid is directed tosaid one side of each piston, the pressure fluid first displaces thefirst piston axially to disengage said locking means and the secondpiston is then actuated by said pressure fluid to rotate the clampmember and when the locking means are disengaged and the pressure fluidis directed to the other end of each piston, the'second piston isaxially displaced to rotate I the first piston and clamp member to aposition where the locking means register and then the first piston isaxially displaced to engage said locking means.

2. A fluid actuated clamp as called for in claim 1 wherein the twocylinders have their axes disposed transversely of one another.

3. A fluid actuated clamp as called for in claim 1 wherein said meansinterconnecting the two pistons includes interengaged gear and gear rackportions.

4. A fluid actuated clamp as called for in claim 3 wherein said gearrack portion is operatively associated with the second piston andwherein the gear portion is operatively associated with the firstpiston; the axes of the two pistons being transversely related and thegear and gear rack portion being adapted to accommodate axial movementof the first piston transversely of the gear rack portion associatedwith the second piston.

5. A fluid actuated clamp as called for in claim 1 wherein said lockingmeans comprises a roller journalled in said first cylinder on agenerally radially extending axis and an axially extending slot in thefirst piston in which said roller is adapted to engage, said slotextending to one end of said first piston and said end of said firstpiston lying in a plane generally perpendicular to the axis of the firstcylinder and adapted to be engaged by said roller when said roller andslot are out of registration.

6. A fluid actuated clamp comprising means forming a first cylinder, apiston movable axially in said cylinder, a piston rod connected to thepiston, a clamp member operatively associated with the piston rod,locking means on the cylinder and piston adapted, when incircumferential registration, to interengage when the piston isdisplaced to one end of the cylinder for preventing rotation of thepiston and the clamp member, said piston being displaceable toward theother end of the cylinder to release said locking means and therebypermit rotation of the piston and the clamp member, said piston having agear portion connected thereto, means forming a second cylinder, asecond piston movable axially in the second cylinder having a gear rackportion operatively connected with the gear portion of the first pistonto rotate the first piston and clamp member in resonse to axialdisplacement of the second piston in its cylinder and means forconducting pressure fluid to one side of both pistons and then to theopposite side of each piston whereby when the first piston and cylinderare interengaged by said locking means and pressure fluid is directed tosaid one side of each piston, the pressure fluid first displaces thefirst piston and clamp member axially to disengage said locking meansand the second piston is then actuated by said pressure fluid to rotatethe clamp member and when the locking means are disengaged and thepressure fluid is directed to the other end of each piston, the secondpiston is axially displaced to rotate the first piston and clamp memberto a position where the locking means register and then the first pistonis axially displaced to engage said locking means.

7. A fluid actuated clamp as called for in claim 6 wherein said lockingmeans comprises a radial projection of the first cylinder and an axiallyextending slot on the first piston in which said projection is adaptedto engage.

'8. A clamp as called for in claim 6 wherein said second piston andsecond cylinder extend axially in a direction transversely of the axisof the first cylinder.

9. A clamp as called for in claim 6 including a third piston in saidsecond cylinder axially opposed to said second piston and also having agear rack portion engaging the gear portion of the first piston.

10. A fluid actuated clamp as called for in claim 9 wherein said gearportion comprises an axially splined cylindrical member projectingaxially from the first piston, said rack portions engaging diametricallyopposite portions of said spline portion.

References Cited UNITED STATES PATENTS 280,668 7/ 1883 Rawlins 92-21,023,518 4/1912 Hansen 17 3-108 X 1,384,661 7/1921 G-uiley 92136 X2,346,820 4/ 1944 Casler et al. 92-2 X 2,957,361 10/1960 Herbenar 92-136X 3,030,935 4/ 1962 Hanes 92--2 MARTIN P. SCHWADRON, Primary Examiner.I. C. COHEN, Assistant Examiner.

1. A FLUID ACTUATED CLAMP COMPRISING MEANS FORMING A FIRST CYLINDER, APISTON MOVABLE AXIALLY IN SAID CYLINDER, A PISTON ROD CONNECTED TO THEPISTON, A CLAMP MEMBER OPERATIVELY ASSOCIATED WITH THE PISTON ROD,LOCKING MEANS ON THE CYLINDER AND PISTON ADAPTED, WHEN INCIRCUMFERENTIAL REGISTRATION, TO INTERENGAGE WHEN THE PISTON ISDISPLACED TO ONE END OF THE CYLINDER FOR PREVENTING ROTATION OF THEPISTON AND THE CLAMP MEMBER, SAID PISTON BEING DISPLACEABLE TOWARD THEOTHER END OF THE CYLINDER TO RELEASE SAID LOCKING MEANS AND THEREBYPERMIT ROTATION OF THE PISTON AND THE CLAMP MEMBER, MEANS FORMING ASECOND CYLINDER, A SECOND PISTON MOVABLE AXIALLY IN THE SECOND CYLINDER,MEANS OPERATIVELY INTERCONNECTING SAID FIRST AND SECOND PISTONS FORCAUSING ROTATING OF THE FIRST PISTON AND CLAMP IN RESPONSE TO AXIALDISPLACEMENT OF THE SECOND PISTON IN ITS CYLINDER AND MEANS FORCONDUCTING PRESSURE FLUID TO ONE SIDE OF BOTH PISTONS AND THEN TO THEOPPOSITE SIDE OF EACH PISTON, WHEREBY WHEN THE FIRST PISTON AND CYLINDERARE INTERENGAGED BY SAID LOCKING MEANS AND PRESSURE FLUID IS DIRECTED TOSAID ONE SIDE OF EACH PISTON, THE PRESSURE FLUID FIRST DISPLACES THEFIRST PISTON AXIALLY TO DISENGAGE SAID LOCKING MEANS AND THE SECONDPISTON IS THEN ACTUATED BY SAID PRESSURE FLUID TO ROTATE THE CLAMPMEMBER AND WHEN THE LOCKING MEANS ARE DISENGAGED AND THE PRESSURE FLUIDIS DIRECTED TO THE OTHER END OF EACH PISTON, THE SECOND PISTON ISAXIALLY DISPLACED TO ROTATE THE FIRST PISTON AND CLAMP MEMBER TO APOSITION WHERE THE LOCKING MEANS REGISTER AND THEN THE FIRST PISTON ISAXIALLY DISPLACED TO ENGAGE SAID LOCKING MEANS.